Effect of clinoptilolite addition on nutrient removal in a membrane bioreactor

This work aimed to investigate the efficiency of nutrient removal in a modified membrane bioreactor (MBR) used for treatment of wastewater containing high level of ammonium. Due to high selectivity of ammonium for clinoptilolite (a natural kind of zeolite) and its unique characteristics, this sort of clay was studied in combination with MBR. Experiments were in two parallel simultaneous MBRs with an hydraulic retention time (HRT) of 8 h within 33 days. Then, the control membrane bioreactor without clinoptilolite (CMBR) and the zeolite membrane bioreactor with clinoptilolite (ZMBR) were studied. Thereafter, nutrient removal from synthetic wastewater in the CMBR and ZMBR were compared. In ZMBR, about 24% more N-NH4 removal was achieved owing to combination of nitrification and cation exchange. It was also found that ZMBR application resulted in 10% increase in TN removal in comparison with CMBR. In contrast, no significant difference was observed in chemical oxygen demand (COD) removal. Only low amounts of nitrate and phosphate were removed during the first days of experiments. The results demonstrated that clinoptilolite is highly effective in reducing ammonium content of wastewaters.